Glass

ABSTRACT

Glass which after adjustment of the surface conductivity by heating in a reducing atmosphere is particularly suitable for use in a continuous channel dynode and which has a composition within the following limits in percent by weight: SiO2 20- 48 PbO 25-35 combinedAl2O3 &lt; OR = 5 Bi2O3 10-35 45-70 B2O3 &lt; OR = 3 CaO+SrO &lt; OR = 8Na2O &lt; OR = 4 MgO &lt; OR = 7Combined K2O &lt; OR = 5 2-8 Sb2O3 &lt; OR = 2Li2O

United States Patent [1 1 Trap *Dec. 4, 1973 41 GLASS 7 [75] Inventor: l-lendrikus Johan Lodewijk Trap, Fri-{nary 'P Curtis Emmasingel, Eindhoven Assistant Examiner-Mark Bell Netherlands Attorney-Frank R. Trifari [73] Assignee: U.S. Philips Corporaton, New York,

[ Notice: The portion of the term of this [57] ABSTRACT patent subsequent to May 16, 1989, has been disclaimed. Glass which after adjustment of the surface conductivity by heating in a reducing atmosphere is particularly [22] Filed 1971 suitable for use in a continuous channel dynode and [21] Appl. No.: 130,467 which has a composition within the following limits in percent by weight:

[30] Foreign Application Priority Data Apr. 16, 1970 Netherlands 7005457 SiO -48 PbO -35 combined 52 U.S. Cl. 106/53, 106/54 315: 2 2281 0 5 [51] Int. Cl. C03c 3/10, C03c 3/04, C03c 3/30 2 4 M 7 [58] Field of Search 106/53 K20 5 53 sbzoa 2 U 0 5 [56] References Cited UNITED STATES PATENTS 1 Claim, No Drawings 3,470,002 9/ 1969 DiMarcello et al 106/49 GLASS The invention relates to a range of glass compositions which are particularly suitable for use in 'a continuous channel dynode. This dynode consists of a body having two parallel end boundary faces and being provided with a plurality of channels which are either or notat right angles to the said end boundary faces and which are open at both ends. Both end boundary faces are coated with an electrically conducting layer and a voltage difference is applied therebetween. Under the influence of the electric field thus obtained electrons move through the said channels from one side of the electrode to the other. I

The walls of the channels consist of a material having a suitable surface resistance which'has a secondary emission factor of more than I at the electron speed caused as a result of the conventional voltage differ-- ence. Consequently, for each electron impinging upon the wall an average of more than one electron returns.

Several methods are known for the manufacture of a glass body for such a dynode which has a diameter of for example 3 to cm and a thickness of l to 2% mm and a plurality of apertures of 10" per sq.cm having an average diameter of approximately 11. per aperture.

The method starts from a glass tube which is drawn out while being heated. The obtained tubes are bundled and the assembly is again drawn out, bundled and combined in a jig and heated until the material of the walls of the tubes is mutually connected together and fills up pressure so that a better mutual flowing together of the tubes takes place. After completion of the glass body,

sio, 3o 70 PbO 6-30 A|,o 05-10 ago. 2-4s a,o, s s CaO-l-SrO s s Na,0 s e MgO 0.5-7 too 5 l0 sb,o s 2 sic. b 12.

combined -70 Ano s 5 ago, l0-35 8,0 5 '3 CaO+SrO S 8 Na,0 S 4 MgO s 7 combined K 0 S Sb,O;, S 2

Four glasses accordingto the invention (nos. 2, 3, 5

' and 6) are given by way of example inthe Table below together with their softening points (S; this is the temperature at which the viscosity is 10 poises) in C and .the value of log a right after the reducing treatment at an optimum temperature. The symbol represents the specific surface resistance in ohms per squaresurface. The Table also states the variation of the surface resistance l/a da/dt wherein t is the time in hours. Finally the Table states two compositions l and 4 having an adm jiblsrvar at sn fth te i fi s e- Cornposition in percent by weight 10 4 S log a 1 da Number S102 A1203 N820 K20 Pbo Blzog sbzos LnO (1.) (=0) a a? this core is removed from the dynode. One of the core materials most frequently used consists of thin metal wire, for example, molybdenum wire having a diameter melting the assembly together and subsequently removing the core by chemical process. a

A range of glass compositions has been discribed in prior United Kingdom Pat. application No. 54,437/69 not yet published in the name of the applicant (US. Pat. application Ser. Now 873,091 now US. Pat. No. 3,663,247), which range may be used on its own, that is to say, without a substrate glass for the manufacture of a dynode in accordance with the above-described technique while using metal wire as a temporarycore. It is true that these glasses melted in an oxidizing atmosphere do not have the required level of the electrical conductivity but this conductivity is achieved by means of a reducing post-treatment at an increased temperature of the finished glass body for the dynode. I

The said glasses have a composition within the range limited as follows in percent by weight:

Molybdenum wire having a thicknessof 20 p. and surrounded by a tube of one of the glasses 2, 3, 5 or 6 was jointly passed through a vertical furnace, the wire moving at a faster rate than the tube. Just before emerging had melted together and the interstices were tilled up.

The bundles were sawn to sheets having a thickness of 1.5 mm.

The molybdenum wires were subsequently electrolytically dissolved in weak alkaline bath containing ammonia and sodium hypochlorite at a clamping voltage of 6 volts and under reversal of the current direction over a period of 10 seconds. Sebsequently the obtained glass body was thoroughly rinsed, dried and heated for deposition.

What is claimed is:

1. Glass which is particularly suitable for use in a continuous channel dynode after adjustment of the surface conductivity by heating in a reducing atmosphere, consisting essentially of the following composition in percent by weight.

SiO, 20-48 PbO 25-55 combined M 0, 5 5 Bi,0 l-35 45-70 [3,0 5 3 CaO+SrO s 8 greater than 1 and a controlled time change of surface conductivity after said heating in a reducing atmosphere.

4 g;;g; UNITED STATES PATENT OFFICE:

I CERTHFECATE 0F CORRECTION Patent No. 3776743 Date d December 4, 1973 Inventofls) I-ENDRIKUS JOHAN LODEWIJ'K TRAP It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Columns 1 and 2, between lines 38 and 47 Line number 1 under Na O, "1.5" should read --l.4- Line number 2 under Bi O "13.2" should read -l3.l--

Signed and sealed this 16th day of April 19%.

(SEAL) Attest:

EDWARD PhFLln'TOl-HERJH. G. MARSHALL DANN Attesting Officer Commissioner of Patents 

